The purpose of this investigation was to compare skeletal muscle protein turnover in response to an acute endurance exercise bout in trained male and female runners. Measurements were taken of mixed muscle fractional synthetic rates and breakdown rates in the vastus lateralis muscle of runners (M = 6; F = 6) following a 75-minute run at 70% VO2peak.

Fractional synthetic rates post-exercise were similar between genders. Breakdown rates post-exercise were greater for females than males and net balance was more negative for females than males.

Implication. These findings suggest that endurance exercise may be more catabolic, with respect to skeletal muscle protein utilization, in female than in male endurance athletes.